An 18-year-old woman was charged on Tuesday, in connection with an alleged failed attempt to bomb London in July last year, two weeks after the July 7 attacks on the capital's transport network, police said.
The teenager, who was not named, is due to appear at City of Westminster Magistrates' Court on Wednesday, the Metropolitan Police said.
She is charged with "knowing or believing" one of the men alleged to have been behind the July 21 plot, Yassin Omar, had been involved, a police statement said.
She is also accused of having information that may have helped in Omar's arrest but failing to tell the authorities "as soon as reasonably practicable".
Two men aged 19 and 24, who were arrested along with the woman last Wednesday, were released on Monday evening without charge, police added.
Six men are due to face trial charged with planning to kill commuters on three subway trains and bus on July 21, mimicking the suicide attacks a fortnight earlier by four British Muslims.